Sharp CD-C422 Service Manual page 34

CD-C422/C422C/C2800/C2800C
• Playback can only be performed when a disc is
loaded.
Is the Focus servo active? (Can you hear it working?)
Yes
Does the DRF signal change from "L" to "H"?
Yes
Is HF waveform normal (see the Fig.34-1, 2)?
Yes
Check the tracking system.
HF
1.0V/DIV
0.5µsec/DIV(DC)
(When playing
back the disc)
Figure 34-1
• Check the tracking system.
Check waveform of IC1 pin 7 (TE).
The waveform shown in
Fig.34-3 appears, and no-
disc state appears soon.
Play is possible in
TEST mode.
Data cannot be read.
Tracking servo is
inoperative.
Yes
Although IL is possible,
Yes
play is impossible.
Yes
5ms
1.00 V
IC1 7 TE
5 ms
5.0 V
IC1 54 DRF
Check the laser diode driver.
No
Check the area around IC1(16) - (21) (focus servo circuit).
If the disc is not turning, the DRF
No
should not change to "H".
No
Level is abnormal.
Waveform is unstable.
0.5s
1.00 V
IC1 16 FD
0.5s
10.0 V
IC2 13 CLV+
0.5s
10.0 V
IC1 54 DRF
0.5s
2.00 V
IC1 7 TE
Check the periphery of IC 1
pin 8 to pin 15, and IC 5 to
Yes
CNP2.
Normal jump is impeded,
Yes and the program top
cannot be reached.
Check the VCO-PLL system.
Figure 34-3
– 34 –
Yes
Check the spin system.
Yes
Check the periphery of
IC1 pins 41 and 42.
Yes
Check the spin system.
Waveform in case of
normal play-back
2
1
3
4
Figure 34-2
Check the periphery
of IC 1 pin 14.
Yes
4
3